Throughout the decades what lamps took top spot and what lamps were average (for the time)

I'm primarily focused on HID lamps between the decades of 1950 to 2000.

Did each company have a strong suite?

I assume in the American market Westinghouse wins in the mercury department am I right?

What about halides, high and low pressure sodium lamps?

Low pressure sodium has to be GECs Supersox, SON was Osrams NAV German plant in the 90s, and Philips’s HPL was the most popular mercury lamp used here for street lighting, as for halide lamps, first prize has to go to Thorns MBIF  

Philips Master SON lamps of the 90s to early 00s were great, that was what's mostly used around my town. Osram Germany SON (NAV) and MBFs (HQL) seems to have been as good

Philips MBF we didnt have many but i have my own one in 125W from the late 90s, with very little use. It is noticably brighter and the color is better than today's MBF lamps

Did the German plant shut down? Or did their quality just bottom out?

German Osram factories are no more I think. At least the Augsburger fluorescent factory shut down this year.

Here at least the utility company I work for we used to and still use Philips SON (PIA) Plus sodium lamps. In the past the HPMV and MVSB lamps were from various makers but mostly Osram and Radium. In the late 1980s the Japanese Iwasaki EYE did try to enter the market but sadly failed due to overpriced lamps.